explode custom field not working

hi
i am trying to use this code to explode data from custom field by name (schools) which includes data like : one,two,three
but it keeps returning this error

Warning: trim() expects parameter 1 to be string, array given in C:\xampp\htdocs\***\wp-content\themes\***\schools.php on line 20

anyhelp ?

<div class="schools_names">
		<?php			

		$school = get_post_meta($post->ID, 'schools', false);
		$school = explode(',' , $school);

		?>
		<h3>colleges:</h3>
		<p>
		<?php
		foreach($school as $src)
		{
		echo '<a href="#" target="_blank">'.trim($src).'</a> - ';
		}
		?>
		</p>
	</div>